问题补充:
— Has Jack finished his homework yet?
— I have no idea;he __it this morning.
A. was doing
B. had been doing
C. has done
D. did
答案:
(答案→)A. was doing
B. had been doing
C. has done
D. did
解析:
题干没有构成“过去的过去”,不可选B。如选C、D则表示动作已完成,与have no idea相矛盾。过去进行时表示过去某段时间或某一时刻正在进行的动作,不涉及结果,正好附合题干语境。